The present invention relates to a device for automatically adjusting the frequency of activation of a motor vehicle windscreen wiper which is driven by a motor.
As is known, windscreen wipers both for the front windscreen and for the rear window are driven by motors which are activated by the driver by means of a control switch when its operation is considered necessary. The continuous operation of the windscreen wiper is not necessary, however, in certain meteorological conditions characterised by intermittent drizzle or dampness, fog, sleet, etc. In fact it is irritating for the driver so that on some cars there has been also provided a slow speed functioning of the windscreen wiper, which the user can employ in the above described visibility conditions. There have also been provided devices for controlling intermittent operation of the windscreen wiper at a fixed frequency; even this, however, is sometimes not satisfactory; either it seems to be too infrequent (the visibility deteriorates excessively during the delay time), or else too frequent (visibility remains good during the delay time, so that the operation of the windscreen wiper seems more troublesome than useful, especially if the surface of the glass being almost dry causes the characteristic squeaking of the blades).